<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
  <script>
    function fn() {
      console.log('15')
    }

    let interval = setInterval(fn, 3000);
    console.log(interval)
    clearInterval(interval)
    interval = setInterval(fn,3000)
    console.log(interval);
  </script>
</body>
</html>